Arne Höll

Argonne, Physics Division

Regarding Nucleon Electromagnetic Form Factors

Modern, high-luminosity experimental facilities that employ large momentum transfer reactions
are providing remarkable and intriguing new information on nucleon structure. At values of momentum
transfer Q2 > M2, where M is the nucleon's mass, a veracious understanding of
these and other contemporary data require a Poincaré covariant description of the nucleon.
This may be achieved through a covariant Faddeev equation, which describes the nucleon and Delta in
terms of confined quark and nonpointlike confined diquark correlations. The Faddeev amplitudes
provide the necessary input to a Ward-Takahashi identity preserving nucleon electromagnetic current,
which yields the nucleons' form factors. A reliable description of the these form factors requires
a careful consideration of "pion cloud" effects.